New records of soft ticks (Acari: Argasidae) in the Caatinga biome of Brazil, with a phylogenetic analysis of argasids using the nuclear Histone 3 (H3) gene.

In Brazil, 19 species of the genus Ornithodoros (Acari: Argasidae) have been reported. The medical and veterinary importance of Ornithodoros ticks has increased substantially in recent decades, with the discovery of various relapsing fever Borrelia infecting Ornithodoros ticks. Herein, argasid ticks were collected during 2019-2020 from caves, abandoned nests and homes in various regions of Ceará State, Brazilian semiarid-Caatinga biome. In total, 289 ticks were collected and identified into five species: Ornithodoros cavernicolous (176 specimens), Ornithodoros fonsecai (81), Ornithodoros mimon (12), Ornithodoros rietcorreai (4), and a fifth species provisionally retained as Ornithodoros sp. Ubajara. Tick identifications were corroborated by a phylogenetic analysis inferred using the 16S rRNA gene. To extend the molecular characterization, DNA samples were tested by an additional PCR assay targeting the nuclear Histone 3 (H3) gene. Because there were no H3 sequences of argasids in GenBank, we extended this PCR assay for additional Ornithodoros species, available in our laboratory. In total, 15 partial sequences of the H3 gene were generated for 10 Ornithodoros species, showing 0% intraspecific polymorphism, and 1.5-11.6% interspecific polymorphism. Phylogenetic analyses inferred segregated Ornithodoros sp. Ubajara as a potential novel species. Our results also highlight the potential of the H3 gene for deeper phylogenetic analyses of argasids. The present study provides new data for argasid ticks of the genus Ornithodoros in the Caatinga biome. Because some of these tick species are human-biting ticks, active surveillance for the incidence of human infection due to Ornithodoros-borne agents is imperative in the Caatinga biome.

Novel Borrelia Genotypes from Brazil Indicate a New Group of Borrelia spp. Associated with South American Bats.

The bacterial genus Borrelia comprises vector-borne spirochetes that have been classified into three major groups: the relapsing fever group (RFG), the Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner sensu lato group (Bbsl), and the reptile-monotreme group (RMG). All three groups have been associated mainly with ticks and wild animals, especially rodents, birds, and reptiles. Here, we searched for Borrelia infection among 99 vampire bats [Desmodus rotundus (É. Geoffroy)] (Chiroptera: Phyllostomidae) from the Brazilian semiarid region. Through molecular investigation of bat internal organs, haplotypes of a potentially novel Borrelia organism were detected in 5% (5/99) of the bats. Borrelia DNA was detected in the liver, blood, spleen, kidney and brain, suggesting a systemic infection. Phylogenetic analyses inferred from partial sequences of the borrelial rrs and flaB genes indicated that the vampire bat-associated Borrelia sp. of this study form a monophyletic group with a newly reported Borrelia associated with a Colombia bat, distinct from the three main currently recognized groups of Borrelia spp., Bbsl, RFG, and RMG. These novel bat-associated Borrelia spp. from South America might have arisen through an independent event along the borrelial evolutionary history, since previous molecular reports of Borrelia organisms in bats or bat-associated ticks from Africa, Europe, and North America were all classified in the RFG.

In vitro activity of Lantana camara, Alpinia zerumbet, Mentha villosa and Tagetes minuta decoctions on Haemonchus contortus eggs and larvae.

The resistance of gastrointestinal nematodes to anthelmintics has increased the need to evaluate natural products that can replace or assist current strategies to control gastrointestinal nematodes. The objective of this study was to evaluate the effect of decoctions of Lantana camara (DLc), Alpinia zerumbet (DAz), Mentha villosa (DMv) and Tagetes minuta (DTm) on Haemonchus contortus by two in vitro tests. The effects of increasing concentrations of lyophilized decoctions (0.31 to 10mg/ml) were assessed using the egg hatch test (EHT). The decoctions were then tested in the larval artificial exsheathment assay. H. contortus third stage larvae (L3) were exposed to 0.31 mg/ml A. zerumbet and M. villosa decoctions and 0.62 mg/ml T. minuta and L. camara decoctions for 3h and then exsheathment procedure at 10 min intervals. An inhibitor of tannins, polyvinyl polypyrrolidone (PVPP), was used to study if tannins were responsible for the inhibitory effect on hatching and exsheathment of larvae. A. zerumbet, M. villosa and T. minuta showed a dose-dependent effect in the EHT, which did not disappear after the addition of PVPP. No effect was observed for L. camara in the EHT. However, the decoctions inhibited the process of larval exsheathment, which may be related to tannin action because the addition of PVPP reversed the inhibitory effect. A. zerumbet, M. villosa and T. minuta decoctions showed inhibitory activity on H. contortus larvae hatching and exsheathing. The decoctions of these plants could be used to control gastrointestinal nematodes following confirmation of their anthelmintic activity in vivo.

Anthelmintic effect of Eucalyptus staigeriana essential oil against goat gastrointestinal nematodes.

The aim of this study was to evaluate the anthelmintic efficacy of Eucalyptus staigeriana essential oil (EsEO). The in vitro effects of EsEO were determined through the egg hatching test and the inhibition of larval development of Haemonchus contortus. The oil was subjected to acute and subacute toxicity rodents. The in vivo effects were determined through fecal egg count reduction test in goats. 1.35 and 5.4 mgml(-1) EsEO inhibited 99.27 and 99.20% H. contortus egg hatching and larval development. In subacute toxicity of EsEO, all parameters were found to be in the normal range, and histopathological analysis of organs did not present alterations. EsEO efficacy against goat gastrointestinal nematodes was 76.57% at 15th day after treatment. E. staigeriana essential oil showed in vitro and in vivo anthelmintic activity.

[Ovicidal and larvicidal activity in vitro of Eucalyptus globulus essential oils on Haemonchus contortus]. / Atividade ovicida e larvicida in vitro do óleo essencial de Eucalyptus globulus sobre Haemonchus contortus.

The objective of this work was to evaluate ovicidal and larvicidal effects of Eucalyptus globulus essential oil (EGEO) on Haemonchus contortus. The chemical composition determination of EGEO was through gas chromatography and mass spectrometry. Egg hatch test (EHT) was performed in concentrations 21.75; 17.4; 8.7; 5.43 e 2.71 mg x mL(-1). In larval development test (LDT) were used the concentrations 43.5; 21.75; 10.87; 5.43 e 2.71 mg x mL(-1). Each trial was conducted by negative control with Tween 80 (3%) and positive control, 0.02 mg x mL(-1) of thiabendazole in EHT and 0.008 mg x mL(-1) of ivermectin in LDT. The maximum effectiveness of EGEO on eggs was 99.3% in concentration of 21.75 mg x mL(-1) and on larvae was 98.7% in concentration 43.5 mg x mL(-1). The concentration of EGEO that inhibits 50% of the eggs and larvae was 8.3 and 6.92 mg x mL(-1), respectively. The oil chemical analysis identified as main component the monoterpen 1,8-cineol. EGEO presented ovicidal and larvicidal activities in vitro, revealing a good potential for use in the control of sheep and goat gastrointestinal nematodes.